Trestle Tracks -- 73 Piece Builder Set by Fat Brain Toys
A truly mesmerizing marble-track experience! Each set is made up of hollow stacking cubes and a variety of perfectly flat tracks. The paths cut out of each track widen almost imperceptibly from one end to the other, creating an invisible slope that propels the marbles forward. Get creative and discover the wonders of simple engineering.
Fat Brain Toy Co.
Unique marble run with marbles propelled by widening tracks